As described in more detail below, in one conventional type of test socket connector for a PGA IC device, an array of terminals are anchored in an insulating body. Each terminal has a cylindrical receptacle portion for receiving a lead of the device and contact pressure therewith is obtained by a ring of spring contact arms in the receptacles which extend away from the mouth in convergent, circumferentially spaced relation and have hardened free edge portions on free ends which grip an inserted lead, with resilient flexure apart of the arms.
However, disadvantages of such prior structure are that undesirably high insertion and withdrawal forces are necessary to overcome the frictional forces arising from the engagement of the spring arms, necessitated by reliance on laterally applied spring force for electrical contact pressure. Such withdrawal forces are all the more significant in a large grid array, often requiring use of a special extraction tool with possible risk of damage to the device.
Furthermore, variations in diameters or widths of leads result in an undesirable variation in contact force and poor contact reliability. Undesirable variations, with risk of spring strain and permanent damage can also arise from poor misalignment between the leads and spring arms arising from mating when misaligned.